The present invention relates generally to field effect transistor fabrication, and more particularly to engineering of the channel under the transistor to counter short field effects in deep-submicron complementary (CMOS) field effect transistors on the same chip.
When MOSFET gate length is scaled below 100 nanometers (nm), short channel effects become significant factors. Strong or higher implant dose super halo implants are widely used in deep submicron CMOS technology to engineer the FET channel to overcome short channel effects. Super halo implants, however, tend to degrade the source/drain junction capacitance, resulting in slower switching speed of the transistor. What is needed is a method to engineer the channel doping profile without affecting the source/drain junction region to overcome the short channel effects in deep submicron CMOS chips having gate lengths of 50 nm or less.
BRIEF SUMMARY OF THE INVENTION
The present invention is a method for improving the channel doping profile of deep-submicron field effect transistors and MOSFETs. By way of example, and not of limitation, the method involves a highly localized halo implant formed in the channel region but not in the source/drain junction. The halo implant is performed through a gap formed by removal of a temporary spacer. The MOSFET is then further completed.
The resultant device exhibits an increased operating speed over heretofore known similar devices. The instant method improves device density on the chip, enhancing the manufacturing precision and efficiency. Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.